Numerical Simulation Accuracy Study of Underwater Explosion Shock Waves

Abstract

In the numerical simulation study of the underwater explosion, the grid size and the artificial viscosity coefficient of the primary term have a large impact on the calculation results of the peak pressure of the shock wave. Under the condition of predetermined calculation accuracy, it is of great significance to quickly determine the grid size and artificial viscosity for numerical calculation. For this reason, based on LS-DYNA finite element software, a two-dimensional underwater explosion numerical calculation model of 78 g trinitrotoluene (TNT) was established to analyze the influence of the grid size and the viscosity coefficient of the primary term on the peak pressure of the underwater explosion shock wave and the overall calculation error. The results show that with the increase in the grid density factor, the sensitivity of calculated peak pressure to the grid decreases. When the grid density is larger, a small primary term coefficient will cause the relative error between the calculated peak pressure and the empirical formula value to increase. On this basis, the relationship among the error, grid size, and viscosity coefficient within 20% is obtained, and an error prediction model that can be used to quickly determine the grid size and the artificial viscosity coefficient of the primary term is constructed. Through the underwater explosion calculation of cylindrical TNT charge (aspect ratio of 1) and spherical TNTcharge in the range of 0.2–5 000 kg, the universality of the prediction model is verified, which can provide a reference for the numerical simulation of underwater explosion shock wave in the two-dimensional near-field range.

Keywords

• underwater explosion
• numerical simulation
• grid size
• artificial viscosity coefficient
• error prediction model